Using boring machines for drilling horizontal boreholes under a roadway or other obstruction is a well-known practice. The process of providing such horizontal boreholes is generally referred to as "trenchless" digging, since an open trench is not required. Examples of horizontal boring machines are disclosed in U.S. Pat. Nos. 4,936,708 to Perry; 3,902,563 to Dunn; 4,679,637 to Cherrington et al.; 4,694,913 to McDonald et al.; 4,674,579 to Gener et al.; 4,790,394 to Dickinson, M. et al.; 3,451,491 to Clelland; and 4,024,721 to Takada et al. However, some of these known horizontal boring machines require a relatively deep ditch or pit in order to both launch and retrieve the downhole boring tool and drill string. A system which uses launching and retrieving pits is shown in FIG. 1 of the cited '913 patent.
Other boring systems do not require launching or retrieving bits, as shown, for example, in FIG. 2 of the cited '913 patent. The known systems, however, use complex and expensive heads. Others use a head containing complex fluid passages and nozzle supplied by a high pressure fluid which does the cutting. These known heads are cast or intricately welded and/or machined, since the drilling portions are formed integrally with the body and typically are of complex three-dimensional configurations compared with the concept of simply using a flat planar rectangular blade. Although some heads, particularly those which rely upon high pressure fluid for cutting do little or no mechanical cutting with the head itself, for simplicity the most forward element attached to a drill string will be referred to herein generally as a drill bit unless specific situations dictate otherwise, for example, when describing the subject invention in detail.
Various forms of drill bits, i.e., the leading or cutting edge of a downhole tool, are also well known. Examples of drill bits are disclosed in U.S. Pat. Nos. 2,196,940 to Potts; 2,324,102 to Miller et al.; 2,903,239 to Standridge; 2,350,986 to Collins; 2,686,660 to Storm; 2,122,063 to Hughes; 1,766,202 to Thompson; and 4,306,627 to Cheung et al. Some of these bits use cutting blades, fluid cutting jets, or combinations of both blade and fluid cutting. Known drill bits, however, have problems which prevent them from efficiently and effectively boring a primarily horizontal hole under a wide range of operating conditions and soils.
There are also instances of the nozzle of a directional head becoming plugged while boring in sandy, loose soil conditions. This primarily occurs when pressure is reduced to add a drill pipe and downhole particles enter the fluid passageway. This loss of flow can cause damage to the transmitter if boring is continued without fluid.
There has also been a need to simply, economically and safely improve the apparatus used when breaking a joint between a drill pipe and a rotary spindle with saver sub, adding a drill pipe and/or removing a drill pipe. Generally, either relatively expensive hydraulic systems or relatively unsafe hand operated systems are used to attempt to lock and unlock a drill pipe when one is trying to tighten or loosen a drill pipe from a saver sub or tighten or loosen a second drill pipe relative to the first drill pipe. For example, oftentimes a standard pipe wrench is hand held while the pipes or the saver sub are rotated relative to each other. A greater than expected movement of the drill string or an accidental rotation of the string in a direction opposite to that desired, can result in an operator having his or her hands pinched against the frame or result in the wrench being launched as a dangerous projectile. Known modifications such as a wrench-holding box just add to the difficulty in attaching a wrench to the pipe and present pinch point problems themselves.